Comparing the vertical distribution of iron in the eastern and western North Pacific Ocean

Abstract

Labile dissolved Fe (<0.22 μm) in the western (165°E) and eastern (165°W) North Pacific Ocean had nutrient- and apparent oxygen utilization (AOU)-like profiles characterized by surface depletion and deep enrichment (5-3000 m depth). Dissolved Fe concentrations in the deep-water column at the mid-latitudes were approximately one-half lower in the eastern region (0.5-0.8 nM) than in the western region (0.8-1.3 nM) although the dissolved Fe concentrations in the surface mixed layer in both regions were extremely depleted to 0.1-0.2 nM. Surprisingly, the labile particulate Fe concentrations (≤∼0.1 nM, total dissolvable Fe minus labile dissolved Fe) throughout the water column at low latitudes in the eastern region were extremely lower than those (∼0.5-1 nM) in the western region. It is suggested that the low Fe levels in the eastern mid-latitude oceanic region are primarily due to the lower atmospheric Fe supply in the eastern region. Copyright 2006 by the American Geophysical Union.